The hard disk stores a byte by some kind of magnetism.
If I don't touch that byte on the disk for a long time, would it
lose magnetism and hence that byte of information?
After how long would that happen?
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> The hard disk stores a byte by some kind of magnetism.
Well, not quite. There is complex modulation, ECC codes,
and other things. Essentially the idea is correct, though.
> If I don't touch that byte on the disk for a long time, would it
> lose magnetism and hence that byte of information?
Yes.
> After how long would that happen?
Nobody quite tells. Component life of HDDs is 5 years,
according ro the manufacturers. So unless that specific
surface areas is bad (very rare today, all bad areas
are reliably mapped out), 5 years is not an issue.
Personally I would expect to see problems with
good writes not before 10 years. But that is just my
intuition. It could be longer.
There are things you can do to stretch the time until
magnetization is lost. Running a full surfacte scan
(e.g. in the form of a long SMART selftest) periodically
will have the disk recognize and rewrite potenially
problematic data sectors.
> There are things you can do to stretch the time until
> magnetization is lost. Running a full surfacte scan
> (e.g. in the form of a long SMART selftest) periodically
> will have the disk recognize and rewrite potenially
> problematic data sectors.
I am thinking to ghost the disk periodically
so as to re-magnetize the idle data files....
that means buying a hard disk of the same size,
but maybe faster.
I am not a hard disk engineer so I am not
conveying my ideas correctly.
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Arno Wagner wrote in news:69in2bF3127kiU1@mid.individual.net
> Previously "Man-wai Chang ToDie (33.6k)" <toylet.toylet@gmail.com> wrote:
>
> > The hard disk stores a byte by some kind of magnetism.
>
> Well, not quite. There is complex modulation, ECC codes,
> and other things. Essentially the idea is correct, though.
>
> > If I don't touch that byte on the disk for a long time, would it
> > lose magnetism and hence that byte of information?
>
> Yes.
>
> > After how long would that happen?
>
> Nobody quite tells. Component life of HDDs is 5 years,
> according ro the manufacturers. So unless that specific
> surface areas is bad (very rare today, all bad areas
> are reliably mapped out), 5 years is not an issue.
>
> Personally I would expect to see problems with
> good writes not before 10 years. But that is just my
> intuition. It could be longer.
>
> There are things you can do to stretch the time until
> magnetization is lost. Running a full surfacte scan
> (e.g. in the form of a long SMART selftest) periodically
> will have the disk recognize and rewrite potenially
> problematic data sectors.
Now tell us, babblebot, what the point of that is when it still looses
its servo data and the drive won't be able to find your precious data,
however good and strong it may be.
>> If I don't touch that byte on the disk for a long time, would it lose magnetism and hence that byte of information?
> In theory, yes.
When the disc is being rotated,
it would subject itself to a field.
Would that mere rotation kill the byte earlier?
--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
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Previously "Man-wai Chang ToDie (33.6k)" <toylet.toylet@gmail.com> wrote:
>>> If I don't touch that byte on the disk for a long time, would it lose magnetism and hence that byte of information?
>> In theory, yes.
> When the disc is being rotated,
> it would subject itself to a field.
> Would that mere rotation kill the byte earlier?
Yes, but there are several orders of magnitude in
fild strength difference. It will not matter in practice.
--
@~@ Might, Courage, Vision, SINCERITY.
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
/( _ )\ (Xubuntu 7.10) Linux 2.6.25.4
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On Wed, 21 May 2008 19:26:28 +0800, "Man-wai Chang ToDie (33.6k)"
<toylet.toylet@gmail.com> put finger to keyboard and composed:
>
>The hard disk stores a byte by some kind of magnetism.
>
>If I don't touch that byte on the disk for a long time, would it
>lose magnetism and hence that byte of information?
>
>After how long would that happen?
Refreshing your data may get around that problem, if it is a real one,
but there would be no way for the user to refresh the embedded servo
information that was prerecorded at the factory.
Life of a byte on the hard disk 
Linear Mode
